I plug my 7.3 powerstroke in because its a HEUI motor. (the oil drives the injectors). I fire it up and it runs smooth and the heat is already warm. If I dont plug it in, it fires right up but I dont get heat until I hit the parking lot at work (2 miles away haha) and I would like t get it at operating temp every time it runs. In my experience, the dcummins and duramaxes run alot better cold/start up easier because they dont rely on the cold thick oil that pumps through the injectors like the 7.3/6.0 strokers.